A glass of composition 85% SiO2 - 15% K2O is to be surface strengthened by ion exchange. To this end, two identical specimens approximately the size and shape of credit cards are soaked for the same amount of time at 850 ∘C. Sample A is soaked in NaCl and sample B is soaked in KCl. From the list below, select the statements that are true.

The yield strength of Sample A will decrease while the yield strength of Sample B will increase.
The yield strength of Sample A will increase while the yield strength of Sample B will decrease.
The yield strength of both Samples A and B will increase.
The yield strength of both Samples A and B will decrease.
The yield strength of Sample A will decrease. There will be no change in the yield strength of Sample B.